but I don't get why is that. Nothing worked, so I eneded up deleting all html and all javascript because it has to start working at some point. So I have empty files.
Just made div #contacts, included jquery and app.js which I am wrinting.

in app.js only put the code

$(function() {
// Stuff to do as soon as the DOM is ready;
$('#contacts').html('sudas');
});

and finally it started to work :D wow. IF this would not have worked then I really would not understand.

So I Ctrl + Z both html and app.js files to get back where I was.

And I see the difference.

Original document ready was like this:

(function ($) {
...
} (jQuery));

But my wokring code was as you saw

$(function() {

And this difeerence made it work. FML.

Can somebody explain what is the difference? I thoguht its the same document ready.
ANd how this could work earlier? I mean